The present invention was initially targeted, but not limited, to the process of cleaning oil refinery storage tanks. Typically, there is a heavy sediment which must be removed from the bottom of the tanks during the cleaning process. The sediment is unusable hazardous waste which must be disposed of at an appropriate dump site. The sediment can further be described as a highly viscous hydrocarbon containing notable levels of scale and sand.
The present method for removing such sediment requires the addition of a light hydrocarbon, such as diesel, to lower the viscosity level, then picking up the treated sediment with a vacuum truck. The additive is necessary because the vacuum truck cannot produce enough suction to pick up highly viscous sediment. Sediment volume increases approximately twenty percent as a result of the additive process. The hydrocarbon additive is then transported along with the sediment to either be extracted from the sediment at an additional cost or disposed of with the hazardous waste.
Another method of interest for removing tank sediment is the use of a high strength industrial vacuum. This method does not require the light-hydrocarbon additive, discussed in the previous method, because the suction produced from these vacuums is adequate for picking up highly viscous tank sediment. High strength vacuums are not currently used for tank cleaning because the collection container for these vacuums can only hold a few cubic yards of sediment. When the container is full, the cleaning process is halted, the unit is moved to a dump site and emptied. The lost time of constantly emptying the container excludes this as a feasable method for cleaning tanks.
To overcome the shortcomings of the above methods, the present invention is developed to reduce the volume of hazardous waste and provide a more efficient cleaning system. The present invention collects the sediment by a means similar to that of the industrial high strength vacuum. Yet the present invention is able to expell waste from the collection container on a continuous basis, thus alleviating the need to continuously stop and empty a full container. No additive is needed with the present invention because adequate suction can be maintained to pick up the sediment in an untreated state.
The reference to "sediment" and "hazardous waste" above are used only to reveal the initial applications and is not intended to be limiting. In fact, the prototype model of this invention was tested using several materials, such as sawdust, sand, water and mud to name a few.